Handheld motor-driven chain saws of the kind referred to above are used in the colder times of the year at low temperatures such as in the wooded northern regions of Scandinavia, North America and the Soviet Union. The use at low temperatures places special requirements on the internal combustion engine driving the chain saw. The fresh air drawn in by suction by the engine from the ambient air often leads to disturbances in the carburetor system at low temperatures and can lead especially to a freezing, for example, of the throttle flap or the main nozzle.
To prevent the above-mentioned operational disturbances, German Patent No. 3,604,166 discloses that heated cooling air occurring in the region of the outer surface of the cylinder block of the engine can be conducted directly to the carburetor. A fan wheel driven by the engine is provided for cooling the outer surface of the cylinder block and directs a targeted flow of cooling air over the cylinder block. A component air current is branched off of the cooling air flow heated in this manner and is directed to the carburetor. The heated air directed to the carburetor is, however, not adequately heated at low temperatures because the engine operates at idle especially between the individual cuts made with the saw chain and this idle operation causes the rotational speed of the fan as well as the moved air flow to become sharply reduced. For this reason, the heated cooling air which is now present is not adequate to maintain the carburetor system at a constant temperature. Furthermore, dirt particles or the like become entrained because of the fan and these dirt particles are directed with the component air current to the carburetor system and the engine and can lead to disturbances.